Kyle Isom
41d01edfb4
All import paths updated from git.wntrmute.dev/kyle/mcias to git.wntrmute.dev/mc/mcias to match the Gitea organization. Includes main module and clients/go submodule. Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>
68 lines
2.2 KiB
Go
68 lines
2.2 KiB
Go
package vault
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import (
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"crypto/ed25519"
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"errors"
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"fmt"
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"git.wntrmute.dev/mc/mcias/internal/crypto"
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"git.wntrmute.dev/mc/mcias/internal/db"
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)
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// DeriveFromPassphrase derives the master encryption key from a passphrase
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// using the Argon2id KDF with a salt stored in the database.
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//
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// Security: The Argon2id parameters used by crypto.DeriveKey exceed OWASP 2023
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// minimums (time=3, memory=128MiB, threads=4). The salt is 32 random bytes
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// stored in the database on first run.
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func DeriveFromPassphrase(passphrase string, database *db.DB) ([]byte, error) {
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salt, err := database.ReadMasterKeySalt()
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if errors.Is(err, db.ErrNotFound) {
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return nil, fmt.Errorf("no master key salt in database (first-run requires startup passphrase)")
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}
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if err != nil {
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return nil, fmt.Errorf("read master key salt: %w", err)
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}
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key, err := crypto.DeriveKey(passphrase, salt)
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if err != nil {
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return nil, fmt.Errorf("derive master key: %w", err)
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}
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return key, nil
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}
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// DecryptSigningKey decrypts the Ed25519 signing key pair from the database
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// using the provided master key.
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//
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// Security: The private key is stored AES-256-GCM encrypted in the database.
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// A fresh random nonce is used for each encryption. The plaintext key only
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// exists in memory during the process lifetime.
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func DecryptSigningKey(database *db.DB, masterKey []byte) (ed25519.PrivateKey, ed25519.PublicKey, error) {
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enc, nonce, err := database.ReadServerConfig()
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if err != nil {
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return nil, nil, fmt.Errorf("read server config: %w", err)
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}
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if enc == nil || nonce == nil {
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return nil, nil, fmt.Errorf("no signing key in database (first-run requires startup passphrase)")
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}
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privPEM, err := crypto.OpenAESGCM(masterKey, nonce, enc)
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if err != nil {
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return nil, nil, fmt.Errorf("decrypt signing key: %w", err)
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}
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priv, err := crypto.ParsePrivateKeyPEM(privPEM)
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if err != nil {
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return nil, nil, fmt.Errorf("parse signing key PEM: %w", err)
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}
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// Security: ed25519.PrivateKey.Public() always returns ed25519.PublicKey,
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// but we use the ok form to make the type assertion explicit and safe.
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pub, ok := priv.Public().(ed25519.PublicKey)
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if !ok {
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return nil, nil, fmt.Errorf("signing key has unexpected public key type")
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}
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return priv, pub, nil
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}
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